Interaction of helium–vacancy clusters with edge dislocations in α-Fe

Molecular static calculations were performed to evaluate the formation energies and binding energies of helium–vacancy (He–V) clusters in and near the core of an a/2<1 1 1>{1 1 0} edge dislocation in α-Fe with empirical potentials. The formation energies of these He–V clusters and their binding energies to the dislocation depend on the helium-to-vacancy ratio of the clusters. For the ratio equal to or larger than 1, the helium–vacancy clusters have negative binding energies on the compression side of the dislocation and strong positive binding energy on the tension side. However, for the ratio less than 1, the He–V clusters have positive binding energy on the both sides near the dislocation core. On the slip plane, the binding energies of the He–V clusters to the dislocation depend on not only the helium-to-vacancy ratio, but also the cluster size.